This invention relates to a self-lubricating bearing for oil-filled machines, and more particularly to a rotor bearing for use in submersible oil-filled motors.
Submersible pumps are typically centrifugal pumps that are driven by submersible motors which rotate a shaft extending from the motor to the pump. Motors utilized to drive such pumps for oil and water production may vary in length from approximately six to over thirty feet in length. Such motors typically have a stator secured within a tubular outer housing and a rotor secured to the shaft which rotates within the stator.
Because of the length of the motor, rotors are generally made up of a number of rotor sections that may comprise a large number of flat disks, or laminations, that are secured to one another and to the shaft in any way known in the art. For example, the rotors may be keyed to the shaft and have retaining rings at the upper and lower ends thereof to prevent axial movement. The rotor sections are spaced apart longitudinally from one another in the motor. Rotor bearings are utilized in the motor to stabilize the shaft, and are typically located between rotor sections and at the upper and lower ends of the rotor. The rotor bearing generally includes a bearing housing having a sleeve disposed therein. The bearing housing is adapted to engage the inner wall of the stator to prevent rotation of the bearing housing in the motor, and the sleeve is in most instances keyed to the shaft so that the sleeve will rotate with the shaft inside the bearing housing. The bearings must be lubricated so as to prevent overheating and/or premature failure. Therefore, shafts in such motors are typically hollow tubular shafts with axial bores therethrough. The axial bore extends upwardly from the lower end of the shaft and is plugged at the top. A radial port will extend through the shaft and the bearing sleeve at each bearing location and will intersect the axial bore so that oil can be communicated from the axial bore in the shaft to be inner surface of the bearing housing to lubricate the sleeve rotating therein. While such a configuration works adequately, reliable lubrication of bearings is a concern. There is some question as to whether the oil is adequately distributed, so that the bearings at the top of the motor receive the same amount of oil as those near the bottom, and whether or not such bearings are adequately lubricated. Furthermore, if the axial bore or one of the radial bores becomes plugged one or more bearings may receive restricted oil flow, or no flow at all, which will cause overheating and failure. Bearings that become worn must be replaced, which is time-consuming and costly. There is therefore a need for an apparatus which can create a reliable, constant oil flow rate through a rotor bearing which will allow the bearing to run cooler and which will allow for a longer bearing life.